A conventional medium carrying mechanism provides two subsidiary rollers that are positioned along an outer circumference of one sheet ejection roller in order to correct curl of a sheet on which a toner is fused. The two subsidiary rollers are contacted and pressed to the sheet ejection roller by one leaf spring so that each of the subsidiary rollers press the sheet between the sheet ejection roller and each of the subsidiary rollers to the sheet ejection roller. As a result, the sheet is curved along the out circumference of the sheet ejection roller and the curl of the sheet is removed (for example, see Patent document; Japan Patent Laid-Open Publication No. H7-237804 (Paragraphs [0012] and [0019], and FIG. 2)).
However, with the above-described conventional art, a force applied by a leaf spring to press subsidiary rollers is eased when the sheet reaches a subsidiary roller on an upstream side, and a sheet is guided between a sheet ejection roller and the subsidiary rollers. During the process, depending on types of sheets being fed, there have been failures in carrying sheets. For example, a heavy sheet such as bond paper does not curve along the outer circumferential surface of the sheet ejection roller, and the subsidiary rollers are moved toward an opposite side of the sheet ejection roller due to the heaviness of the sheet. This decreases the ability to carry the sheet so that a carrying failure may occur; that is, the sheet ejection roller and each of the subsidiary rollers does not hold and carry the sheet properly. Similarly, when the elasticity of the leaf spring, which presses the sheet ejection roller, is increased to prevent such a carrying failure of the sheet, a heavy sheet such as bond paper is forced to curve along the outer circumferential surface of the sheet ejection roller. As a result, the sheet may receive damage such as being folded and/or marked by each of the subsidiary rollers. Considering the above failures, an object of the present invention is to provide a device that effectively carries a medium regardless of the types of the media.